Adhesive transfers



ct. 19, 1965 F, w, MACKENZIE 3,212,913

Ammsrv TRANSFERS original Filed June 19, 1962 FIG. I

5 Hal/P017# Pew Aleman/5277 cia United States Patent O 3,212,913ADHESIVE TRANSFERS Frederick W. Mackenzie, London, England, assigner toLetraset Limited, London, England, a British company Continuation ofapplication Ser. No. 203,451, June 19, 1962. This application Mar. 31,1965, Ser, No. 444,321 Claims. (Cl. 117--3.1)

This application is a continuation-in-part of my application Serial No.286,847 filed lune 10, 1963, copending herewith, now abandoned which isa division of my application Serial No. 118,765 filed June 22, 1961, nowU.S. Patent Serial No. 3,131,106 and this application is in addition acontinuation of my application Serial No. 203,451 filed lune 19, 1962and now abandoned.

This invention relates to adhesive transfers (decalcomanias) and moreparticularly to a form of transfer material in which an image, design orprinted matter (hereinafter generally referred to as indicia) may betransferred from a carrier sheet to a further support. The inventionincludes transfer materials, their production and the processes of theiruse.

Transfer materials consisting of a carrier sheet carrying an indiciawhich can be transferred bodily from the carrier sheet to a furthersupport are very well known indeed and a great deal of effort has beendirected to the production of such materials which will permit transfer,in close register, of any indicia with ease, speed and reliability andwhich will give consistently good results.

In the earlier days of the art, attention was mainly directed totransfer materials which required the application of water to releasethe indicia. Such transfer materials were usually difficult to make,complicated in construction, and difiicult to store withoutdeterioration. Moreover the necessity for using a liquid to effect thetransfer gave difficulties in their application and in some casesrendered them useless for desired purposes.

In more recent years attention has been directed to the production oftransfer materials from which the indicia could be transferred withoutthe use of any treatment liquid, so called dry transfer materials. Insome such materials heat is required in order to release the indiciafrom the carrier support, e.g. for the purpose of softening a waxyrelease layer. It has also been proposed, more recently, to apply to thesurface of the indicia a pressure sensitive adhesive so that theindicia, being very firmly adherent to the pressure sensitive adhesivelayer would release from the carrier support and adhere, with the saidadhesive, to another support.

In general, with this latter type of product it has been necessary toprovide a protective sheet over the pressure sensitive adhesive, whichsheet was peeled away as a step immediately prior to the transfer of theindicia to another support. The protective sheet was necessary sinceotherwise the transfer material was impossible to handle as a commercialarticle -owing to its readiness to stick to anything placed in contactwith it, i.e. sheets of such material could not be stacked for packingpurposes. Moreover the necessity for removing the protective sheetimmediately before using the transfer material led itself to two majordifficulties. On the one hand the actual operation of removing theprotective sheet not infrequently pulled away from the carrier sheet thepressure sensitive adhesive and part, or the whole, of the indicia and,on the other hand, even if the protective sheet was peeled off withoutdamage to the other layers it left a material which because of itsreadiness to stick to anything on the lightest contact cou-ld not easilybe manipulated to position it for accurate register of the indicia tothe surface where it was required.

If it is provided that the pressure sensitive adhesive is present onlyin register with the elements of the indicia this difiiculty is overcomebut in practice it is extremely 3,212,913 Patented Oct. 1,9, 1965 icedifficult to maintain exact register in successive printing operationsand it usually arises that the indicia transfers with an edging ofimperfectly registered adhesive. This edge is unsightly and, beingtacky, tends to pick up dirt after transfer so that the transferredindicia may become spoilt in a very short time by the accretion of dirtymarks round the elements of the indicia.

Absolute accuracy of register is difficult to achieve so that suchmethods have usually only been employed where the indicia are -of verysimple form, e.g. straightforward geometrical designs.

Furthermore, dry transfer materials of the type just discussed haveusually used a paper carrier support, sometimes a laminar product of afair degree of complication, which has had a very limited transparencyor translucency (if indeed it was not opaque) so that accuratepositioning of the transfer material, when the transfer is beingeffected, is the more difficult. Moreover, such carrier sheets based onpaper have often suffered from the disadvantage of dimensional variationwith atmospheric conditions, and have often had a serious tendency tocurl.

As a result of very considerable research and experiment it has beenfound possible to overcome the aforesaid difficulties and it is aprimary object of the present invention to provide a form `of transfermaterial such is stable on storage, very simple indeed to use and whichgives consistently good transfers.

According to the present invention there is provided a transfer materialcomprising a light transmitting extensible base sheet printed withindicia on one face and said indicia super-coated with an adhesive, theadhesive being of a character which will not adhere to another surfaceunder light finger pressure but which will adhere to another surfacewhen a substantial pressure is applied to the reverse side of the basesheet, whereby when the base sheet is subsequently lifted away theindicia remains, stuck by the adhesive, on said other surface.

More specifically according to the present invention there is provided atransfer material comprising a carrier sheet consisting -of a sheet oftransparent or translucent lm of high dimensional stability undernormally varying conditions of temperature and humidity but which isreadily capable of stretching on application of tension thereto, indiciain printing ink carried by said carrier sheet, said printing ink beingbased essentially on a polymeric material and containing a plasticisertherefore, and a thin layer of -a pressure sensitive adhesive extendingover the whole of the printed area of the carrier sheet on the printedside, the adhesion between the said indicia and the carrier sheet beingreducible by local stretching of the carrier sheet in the regionthereof, and the pressure sensitive adhesive being substantiallynon-bonding at pressures less than 50 lbs. per square inch.

It is to be noted that if, in a transfer material according to thepresen-t invention the pressure sensitive ad-V hesive layer is omitted,then the application of local pressure to the reverse side of thecarrier causes the printed indicia to separate integrally from thecarrier sheet. This result is achieved by selecting a carrier sheetwhich is readily capable of stretching on application -of tensionthereto and formulating the ink lso that the indicia will so separate onthe local appli-cation of stretching tension to the carrier sheet, i.e.the effect of such stretching must be to apply a force to the indiciawhich is greater than the adhesive force between the indicia and thesupport.

There is thus la 'fundamental difference between the transfer material-sof the present invention and those of the prior 4art referred to above.The prior art materials have relied essentially on the use of a surfaceadhesive of greater Iadhesive power to the transfer surface and to theindicia than the adhesive power of the indicia to the carrier, i.e. thesurface adhesive has acted to pull the indicia away from the support andhold it to the transfer surface. 4In the material-s of the presentinvention, in contra-st, the separation of the indicia from the support`derives essentially from a manipulation of the support and not by thepulling power of some applied adhesive, and the thus-loosened indiciaare simply stu-ck by the high pressure adhesive t-o the transfersurface. IIn consequence it is made possible to employ an adhesive whichis not ya bonding adhesive at low pressures.

Transfer materials according to the present invention are easy to handle4since the pressure sensitive adhesive will not bond to .anything withwhich it cornes into contact unless a substantial pressure is applied.It is accordingly not necessary to provide a protective sheetsemipermanently stuck to the adhesive surface. It is desirable inpractice to interleave the transfer materials with, Ifor example,silicone-treated interleaving paper but this paper does not sticktightly to the Iadhesive layer and will usually separate under its ownweight.

Furthermore, the transparency or translucency of the support -sheetenables the transfer material to be accurately positioned rfor use sincethe indicia can be seen through the back of the sheet. The whole productis stable under normal storage conditions and when required for use itis only necessary to apply it to the surface on t-o which the transferis to be made, and -apply a pressure in excess of 50 lbs. per squareinch to the back of the carrier. The indicia then release from thesupport sheet and become adherent to the said surface. In practice it isusually necessary only to apply pressure to the back of the sheet with ahard object in the area of the indicia, covering at least part of theperimeter of the elements of the indicia, using a sufficient pressure toeffect the release and simultaneous bonding.

The adhesive is applied as a thin layer over the whole surface of theprinted side of the carrier and it is found that, provided it has alower tensile strength than that of the printing ink and good adhesionto the non-printed areas of the carrier, it Will shea-r round theelements of the printed indicia so that only the adhesive coated n theprinted indicia will transfer.

Whilst various types lof translucent or transparent film material-s aresuitable 'for use as carrier sheet-s in the present invention, it isfound that particularly good results are obtained by the use ofself-supporting films formed of polyalkylene derivatives, e.g.polyethylene, polypropylene and copolymers containing at least 90% ofeither of these polyalkylenes.

The preferred material for use is polyethylene ilm made of polyethyleneof density 0.96 g./.m.'l., melt index 0.2 (method of BS 1972); softeningpoint 122 C. for 30 deflection (BS 1493); tensile strength 4200 p.s.i.(BS 2571); elongation at break 100-500%; Young Modulus 2.0 105 p.s.i.;and Water absorption less than .01% vafter 30 days immersion. The abovepolymer has a different molecular structure to conventionalpolyethylene, having linear and more regular polymer chains with verylittle side chain branching, which impart a high degree ofcrystal'linity of about 93%. This structure provides the physical andchemical properties required for use in the present invention namely,stiffness, strength and elongation in very thin lm form, and resistanceto temperature, water and solvents.

The lm suport may be, for example of thickness 0.001 to 0.008 inch andmay have a glossy, matt or -semimatt surface and the transferred indiciawill have a Icorresponding surface. A matt surface to the transferredindicia is sometimes of value where the transferred image is to be used`for photographic reproduction.

The indicia are applied to the carrier support sheet by a printingoperation. The formulation of the ink is yof importance in order that itshould meet the requirements set lforth above, i.e. that it shouldadhere sufficiently` to the -support and yet be freed from the supportby localised stretching of the support. The ink consists essentially ofa high polymer and a plasticiser therefor. Generally it is founddesirable to select a high polymer which, if used alone, would releasespontaneously tfrom the support and then to add to it lsuflicient of aplasticizer as to achieve the desired level -of adhesion to the support.

Thus, for example, a clear ink medium may be prepared from a highpolymer of cellulose nitrate of extra low, low or medium viscosity type,being an ester soluble grade, of nitrogen content of ILS-12.3%, or aspirit soluble grade of nitrogen content 10.5-11.2%. The cellulosenitrate may be employed damped in butanol, or the like, with 65 to 70%polymer solids. The cellulose nitrate is dissolved in a solvent suitablein volatility for the particular printing process, and which does notdissolve, curl or distort the carrier sheet. Aliphatic or aromatichydrocarbon solvents are undesirable, but esters, ether-esters, ketones,alcohols, ether-alcohols, ketonealcohols are suitable on thepolyethylene carrier support referred to above. A particularly suitablesolvent for screen process printing, having low odour and a lowevaporation rate, is ethylene glycol monoisopropylether acetate. A highpolymer solution as thus formulated provides the necessary tensilestrength of the dry ink iilm, but used without the inclusion ofplacticiser would give indicia which would spontaneously release fromthe carrier sheet.

A plasticiser must be added to the lhigh polymer solution to impartexibility according to the known principles of lacquer formulation .andalso to control the release to precisely the required value by a mostcareful control of concentration. Two types of plasticiser may be used;one type is the so called solvent plasticiser which may provide part ofthe plasticiser content and is usually a non-polymeric material of lowvolatility, usually an ester, which is compatible with the high polymerand has a softening or dissolving action on it. Examples are dioctylphthalate, tributylcitrate, dimethylcyclohexyl adipate,trixylenylphospate. The second type of plasticiser is a non drying oil(i.e. non oxidising) modified polyester, compatible with the highpolymer.

The following oils, alcohols and acids may be variously rrployed in theproduction of such polysters:

Castor oil Hydrogenated castor oil Coconut oil Alcohol:

Ethylene glycol Glycerol Pentaerythritol Trimethylopropane Acid:

Phthalic (or anhydride) Isophthalic Terephthalic Adipic Sebacic Aparticularly advantageous plasticisor is a polyglyceryl sebacate, of 72%castor oil content and having a viscosity x-y, Gardner-Holdt scale.

In general terms, using cellulose nitrate as the polymer there may beUsed, for parts of cellulose nitrate, 20 to parts of plasticisor, e.g.55 to 150 parts of a castor- 011 modled alkyd resin or hydrogenatedcastor-oil modiiied alkyd resin.

The PflfhlUlg iIlkS Sed may be clear or pigmented or dyed and it 1sfound to be particularly advantageous to formulate them so that they maybe applied by silk-screen prmtmg methods.

It' Wlu geperally be found suiiicient to so formulate the mk that 1twill adhere to the carrier sheet at pressures below 2 lbs. per squareinch but will release from the carrier sheet at pressures of 50 lbs. persquare in ch or more.

If desired the printed indicia, which may be a clear non-pigmented ink,may be overprinted with a normal type printing ink applied by anyconventional method, e.g. by screen process, letterpress, olset litho,gravure, flexographic or brinzing processes, and this overprinting mayconstitute the means whereby colouration or opacity is imparted to theindicia.

In a preferred form of the invention there is, over the indicia, a layerof a pressuresensitive adhesive having a tack-controlling component thatis believed to take the form of a surface shield. To this end there maybe used a composition which comprises as a first component, an elastomerwhich is intrinsically tacky or which has admixed therewith a resinimparting tackiness thereto, and, as a second component, a substancewhich reduces the tack of the composition to a level not exceeding apeel bond value of and, preferentially, not exceeding 10 grams perlinear inch at a pressure of 0.5 p.s.i., the composition exhibitinggradually greater peel bond values at higher pressures up to a maximumpeel bond value under a pressure of 50 p.s.i., or more.

When such an adhesive composition is used as a layer on a flexible base,it is almost non-tacky so that when placed on the receptor surface itmay be moved into an exact position without -diiculty and without damageto the adhesive sheet or to the receptor surface by premature adhesion.After such positioning, the application of light fixing pressure willlightly adhere the adhesive sheet to the receptor surface and a strongpressure will increase the strength of adhesion up to a maximum adhesionvalue above which higher fixing pressure has no further effect. Thismaximum adhesion value may be predetermined to be such as to permit theadhesive base sheet, or any printed or coated element on such sheetdirectly under the adhesive layer, to be subsequently removed from thereceptor surface without damaging the receptor surface. For example, theadhesive base or element may be removed by pulling off with a piece ofordinary tacky adhesive tape. When using a paper or similarly fragilereceptor surface, an adhesion of 100 grams per linear inch peel bond isa suitable maximum value to avoid paper tear or delamination whenremoving the adhesive base or element.

The fixing pressure required to cause maximum adhesion is essentially ahigh pressure, ranging from 50 p.s.i. to 500 p.s.i. or more, and yhighpressures of 500 or 1,000 p.s.i. are readily achieved by making a seriesof strokes over the back of the adhesive sheet with a stylus orballpoint.

As noted above, the adhesives preferred in this aspect of the presentinvention contain two main components, which, for convenience arereferred to herein as Component 1 and Component 2. Component 1 is anelastomer which is intrinsically tacky or is rendered tacky by the usualtackifying resins and will, accordingly, adhere on contact. Component 2is a substance which reduces tack and prevents the adhesive compositionfrom adhering on light contact but is such lthat, on the application ofa high fixing pressure of 50 p.s.i. to 500 p.s.i. or more, thecomposition will adhere to a predetermined maximum adhesion value and,at pressures below that required for maximum adhesion, Will adhere withproportionally lower adhesion values, until at a pressure of 1/2 p.s.i.,an adhesion of l5 grams per linear inch peel bond, `or less, isexhibited.

Component 1 is preferably an organic polymer of K value at least l0 ormolecular weight 10,000 or more, which is tacky and which yields filmshaving a high elongation. Particular groups of polymers of value are thepolyacrylic or polymethacrylic esters and acids, polyvinyl ethers,polyisoprene including natural rubber, polyvinyl esters,polychloroprene, polyisobutylene, polybutadiene, polybutene andcopolymers of these with each other or with other polymerisablemonomers.

Tackifying resins may be included to increase intrinsic tack such ashydrocarbon resins, terpene resins, and rosin,

6 hydrogenated rosin and their ester and polyesters. Preferred materialsfor Component l are a polyvinylalkyl ether in which the alkyl groupcontains 2 to 4 carbon atoms, or a polybutyl acrylate alone orcopolymerised with methyl acrylate, or a mixture of these or either orboth in admixture with polyisobutylene.

In preferred surface-shield adhesives Component 2 is a substance used ata concentration of 15%-50% by weight of the adhesive composition and isphysically characterised as a substance which is deformable or flowsunder a high pressure of 50-500 p.s.i. and provides an adhesivecomposition with a durometer hardness of units or less (see ASTM676-49T). Chemically, Component 2 may be selected from classes oforganic compounds containing one or more hydrocarbon or hydrocarbonether chains totalling at least l2 carbon atoms which are believed toprovide the low molecular forces responsible for deformability underpressure. Preferably, such compounds have a molecular weight -of 800 orless.

T-o the touch, some of these compounds may appear waxlike, fatty, orgreasy but they are not necessarily waxes and the adhesive compositionis distinctly elastomericor rubbery and does not exhibit wax-likeproperties, such as low scratch resistance, transfer or offsetting underpressure of the type shown by carbon paper, or melting to a thin liquidwhen heated to a relatively low temperature. It is believed that theadhesive composition exists as two phases in which particles of tackyComponent l are shielded by particles, or a surface film, of Component2, until a pressure of 50-500 p.s.i. or more is applied, which causesComponent 2 to flow or deform, and allow Component l to contact Vandadhere to the receptor surface. Therefore, the concentration ofComponent 2, its deformability, its particle size and distribution arefactors which are controlled as required to select the pressure/adhesion curve, the threshold pressure for adhesion and maximum adhesionvalue as may be required for any particular product of this invention.

Particular organic compounds which may be used as Component 2 are longchain hydrocarbons, carboxylic acids of long chain hydrocarbons, andtheir metallic salts, esters, polyesters, amide, nitrile and amine andquaternary ammonium derivatives, alcohol derivatives of long chainhydrocarbons, and polyglycol derivatives.

Especially valueable are the esters of polyhydric alcohols and fattyacids which may be prepared by direct esterification of tihe polyhydricalcohol by the free fatty acid at elevated temperature for some hours,with constant stirring. An alkaline or metallic soap catalyst may beused to accelerate the reaction. Usually, an excess of fatty acids isused over the stoichiometric ratio for the mono or diester; this excessacid may be left in the final product or may be neutralised with sodiumbicarbonate to leave a proportion of metallic soap in the ester.

Suitable polyols and acids are:

Polyol:

Ethylene glycol Diethylene glycol Trimethylene glycol and a propyleneglycol D-Sorbitol Pentaerythritol Fatty acid: Laurie Palmitic StearicThe mono esters of the glycols and the mono and diesters of 'thetrihydric alcohols are particularly suitable since they are 4readilydispersible in cold or hot Water, using an anionic surface active agent.For example, diethylene glycol mono stearate and glyceryl monostearateare readily dispersible in water. Component 2 itself may be surfaceactive which may assist absorption and shielding of Component 1particles.

It is sometimes advantageous to include in Component 2 a smallproportion of a polyglycol.

According to known pressure sensitive adhesive technology transparentllers, such as silica, in the form of line powders, may be incorporatedin the adhesive composition to improve stability, coating or printingproperties and to reduce costs. Such powders may be used in the adhesiveas a third component but if used in high concentration they will reducethe tack of Componentll s-o that a highly tacky form of Component 11,ysuch as polyisobutylene of low molecular weight, must then be used. Theconcentration of Component 2 may be also reduced to compensate for thetack reducing properties of the powder.

In the production of the adhesives useful in practicing the invention itis preferred to form a water-based liquid composition by intermixing asolution, dispersion or emulsion in water of Component 1 with asolution, dispersion or emulsion in water of Component 2. Dispe-rsing oremulsifying `agents may be added to assist in the production ofdispersions or emulsions, e.g. anionic, cationic, ampholytic ornon-ionic surface active agents. Alternatively, an organic solvent-basedliquid composition may be produced by intermixing an organic solventsolution of Component 1 with an organic solution or dispersion ofComponent 2.

The following examples, in which the parts and percentages are byweight, illustrate adhesives used in the invention.

Example 1 An aqueous emulsion is made up of the following components.

Parts Water 45.27 Non-ionic surface active agent 1.2 Anionic surfaceactive agent 0.3 Hydroxyethyl cellulose I0.55 Potassium persulphate 0.33-Borax 0.35 Monomer or monomers (see below) 52.0

Suitable monomers are, for example, vinyl caprate, butyl acrylate, ethylhexyl acrylate and vinyl butyl ether. 'Particularly valuable results areobtained by using butyl acrylate alone or with 20% methyl methacrylate.

All the components except the monomer are dissolved in the water andcharged to a reactor vessel. A slow stream of nitrogen is passed overthe liquid and 10% of the monomer (or mixture) is added with stirring.The temperature is then raised to 75 C. and the rest of the monomeradded over 2-3 hours. This gives a smooth milky emulsion, viscosity50-2000 c.p.s. with particle size of about l1 micron with a molecularweight of 10,000- 200,00 depending on the monomer and reactionconditions. If the emulsion is coated on a exible polyvinyl chlorideiilm at a dry thickness of 0.002 inch, and dried by evaporation, aclearly tacky film is obtained having elastomeric properties and highelongation and will adhere to a receptor surface such as glass underlight contact and will adhere with maximum adhesive when a pressure of1/2 p.s.i. is applied to give a peel bond of 300- grams per inch.

An aqueous viscous dispersion of a fatty acid ester of a polyhydricalcohol, such as glycerol monostearate, is formed from 2 parts of esterand l2 parts of water. To this is added 8 parts of the emulsiondescribed above at 50% solid content, to give a concentration of 33% ofthe ester on the total solids content of the adhesive. This liquidadhesive is a thin paste which may be printed by the screen process onto a polyethylene exible base 0.002 inch thick, and after drying gives adry adhesive layer of 0.0003 inch thickness. This adhesive has a rubberyfeel and is almost nonsticky to the touch and will not adhere to paperor glass under its own weight. At a pressure of 500 p.s.i., the adhesivewill adhere rmly with a peel bond of 75 gramsper inch and may besubsequently peeled away without da-mage to the paper surface.

Example 2 Polyisobutylene or polyvinylibutylether with K values of 10 to65 are tacky materials and are dissolved in aliphatic petroleum, boilingrange fll0 C.l20 C., to provide a solution of up to 50% solids. A 30%dispersion of microcrystalline hydrocarbon wax l75/ 180 F. (ASTM Test)with penetrometer hardness of 1.5 mm. is prepared by dissolving the waxin hot aliphatic petroleum of similar boiling range. parts of waxdispersion are added hot to 50 parts of the adhesive solution toprovide, after drying by evaporation, a very low tack adhesive.

In this specification peel bonds are determined under controlledconditions in which a l inch wide strip of smooth, calendered, uncoatedprinting paper, caliper 0.0015 inch, previously conditioned at 20 C. and55% RH. is placed on the adhesive surface at 20 C. and a uniformpressure of 1/2 p.s.i. is applied for 3 seconds, for example, using aflat weight cushioned 'by 1A; inch foam rubber. The peel bond is thenimmediately determined by peeling off the paper strip at right angles tothe adhesive surface at a steady rate of l inch per 5 seconds, theaverage force required being the peel fbond.

The adhesive may be used over an indicia-printed base made according tothe following example:

A clear ink which has excellent screen printing properties is formulatedas follows:

Parts .by weight 33% solids cellulose nitrate low viscosity nitrogenPLS-12.3% in ethyleneglycol mono isopropyl ether acetate 12500 72%castor oil glyceryl sebacate 2545 Dimethylcyclohexyl adipate 255 Thepolymer to total plasticizer ratio (which controls the releaseproperties) is 100:67 in this ink.

A modification of this ink to include pigment is achieved by theaddition of 6000 parts of rutile titanium dioxide and adjustment of thepolymer to total plasticizer ratio to 100:81.

Such clear or pigmented ink medium is printed through a stainless steelor nylon mesh screen, the design being formed by a hand cut stencil forsimple designs and a photostencil for complex designs, to provide a dryink lrn thickness of 0.0005i0-0002 inch, on a polyethylene film(polyethylene density 0.96 referred to above).

The resulting transfer material may be used in the following manner:

The transfer material is placed, adhesive side down, onto the surfacewhich is to receive the indicia, such as a sheet of drawing paper or lm.The indicia is registered with the surface and then pressure is appliedusing a standard ball-point pen having a .040 inch diameter ball, usinga light writing load of 2 ozs. This constitutes an average pressure of1600 p.s.i. since the pressure band is of .010 inch width, and causes anoticeable stretch in the carrier sheet which exceed the yield point ofthe film and can be seen and felt when the pressure is released. Thepressure is applied as a series of strokes over at least part of theperimeter of each ink area, when uni-directional lifting away of thecarrier lm is desirable. If pressure is applied over the whole of theperimeter of ink area the carrier film may be lifted away in anydirection.

In practice a load of l to 4 ozs. is adequate, the lightest load beingadequate when the nal surface is very soft and permits a largestretching of the carrier sheet and the higher loads when the nalsupport is hard, eg. glass.

The presently preferred form of dry transfer of the present invention,and its method of use, are shown in the accompanying drawing in which:

FIGURE l shows a diagrammatic section of the dry transfer material;

FIGURE 2 shows at left pictorially and at right in section the methodand mechanism of transfer;

FIGURE 3 shows at left pictorially the result of the transfer operationand at right the residual elements of the transfer material in their newlocation.

Referring to these drawings, in FIGURE 1 there is shown the carrier lm 1carrying indicia 2 (one such is shown) and adhesive 3. It will be notedthat the adhesive extends beyond the margins of the indicia to overlaponto the carrier lm 1.

To effect the transfer, the dry transfer material is laid down with thesurface of adhesive layer 3 in contact with a receiving sheet 4.Pressure is applied to the area of the carrier lm 1 behind the indicia 2by means of a ball point pen 5. The effect is to stretch the lm 1 asshown and thus release the indicia 2 from the lm 1. Air thus entersbetween the indica 2 and the lm 1.

The dry transfer material is then lifted away as shown in FIGURE 3. Thearea of adhesive 3 which overlapped onto the lm 1 remains in position onthe carrier lm 1 due to shearing of the adhesive around the edges of theindicia. The indica 2 however is adherent to the receiving sheet 4 bymeans of that part of the adhesive 3 which lay over the indicia 2.

What is claimed is:

1. As a new article of manufacture a dry transfer sheet which comprisesa carrier sheet, an image of film-forming printing ink printed on afront face of the said carrier sheet and having a mechanically breakablebond thereto, and a low-tack pressure sensitive adhesive applied overthe image overlapping onto the said carrier sheet, such that the imagemay be caused bodily to adhere, by means of said adhesive, to areceiving surface, by pressure applied to the rear surface of thecarrier sheet in the region of the image, the cohesive strength of theadhesive, and its adhesive bond to the carrier sheet in the overlapareas, being greater than the adhesive bond established between theadhesive and the receiving surface on application of image-transferringpressure in the area of the image, the said cohesive strength andadhesive bonds being measured in a direction normal to the carriersheet, the adhesive having such limited strength relative tothe strengthof the image and the adhesion thereof by said adhesive to the receivingsurface as to part around the outline of the image when the carriersheet is pulled from the receiving surface after image-transferringadhesion to the receiving surface is produced by applied pressure bothin the area of the image and in the overlap areas.

2. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia offilm-forming ink printed on a front face of the said carrier sheet andhaving a mechanically breakable bond thereto, and a low-tack pressuresensitive adhesive applied over the said indicia and overlapping ontothe said carrier sheet, said adhesive having a Ilow tack at pressures ofsubstantially less than about 50 pounds per-square-inch and asubstantial tack at pressures above about 50 pounds per-square-inch,such that selected individual indicia may be caused bodily to adhere, bymeans of said adhesive, to a receiving surface, by pressure of at least50 pounds per-square-inch applied to the rear surface of the carriersheet in the region of the selected indicia, the cohesive strength ofthe adhesive, and its adhesive bond to the carrier sheet in the overlapareas, being greater than the adhesive bond established between theadhesive and the receiving surface on application of at least 50 poundsper-square-inch in the areas of the indicia, the said cohesive strengthand adhesive bonds being measured in a direction normal to the carriersheet, and the adhesive having such limited strength in relation to thestrength of the indicia and of the adhesion thereof by the adhesive tothe receiving surface as to part around the outlines of transferredindicia when the carrier sheet is pulled from the receiving surfaceafter the adhesive is adhered thereto both in the areas of the indiciaand in the overlap areas.

3. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier film of high dimensional stability undernormally varying conditions of temperature and humidity but which isstretchable on application thereto of a localized stress, a plurality ofseparate indicia of film-forming ink on a front face of the said carrierfilm and having a bond thereto that is mechanically breakable by localstretching of the carrier iilm in the region of the indicia, and alow-tack pressure sensitive adhesive applied over the said indicia andoverlapping onto the said carrier film, such that selected individualindicia may be caused bodily to adhere, by means of said adhesive, to areceving surface, by pressure applied to the rear surface of the carrierfilm in the region of the selected indicia sufficient to stretch thecarrier film locally and thereby break the bond between the carrier lmand the said indicia, the cohesive strength of the adhesive, and itsadhesive bond to the carrier lm in the overlap areas, being greater thanthe adhesive bond established between the adhesive and the receivingsurface on application of said applied pressure, the said cohesivestrength and adhesive bonds being measure-d in a direction normal to thecarrier iilm, the strength of the indicia and of the adhesion thereof bythe adhesive to the receiving surface due to application of said appliedpressure being greater than the strength of the adhesive so that theadhesive ruptures around the outlines of transferred indicia when thecarrier film is pulled from the receiving surface after the adhesive isadhered thereto both in areas of the indicia and in the overlap areas.

4. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia offilm-forming printing ink on a front face of the said carrier sheet andhaving a mechanically breakable bond thereto, and a low-tack pressuresensitive adhesive of a high-tack adhesive component admixed with atack-reducing low tensile strength deformable component applied over thesaid indicia and overlapping onto the said carrier sheet, such thatselected individual indicia may be caused bodily to adhere, by means ofsaid adhesive, to a receiving surface, and to transfer to said :surfaceby localized pressure applied to the rear surface of the carrier sheetin the region of the selected indicia, the cohesive strength of theadhesive, and its adhesive bonds to the carrier sheet in the overlapareas, being greater than the adhesive bond established between theadhesive .and the receiving surface on application ofindicia-transferring pressure, the said cohesive strength and adhesivebonds being measured in a direction normal to the carrier sheet, and thestrength of the indicia, and of the adhesion thereof by said adhesive tothe receiving surface resulting from application of indicia-transferringpressure, being greater than the strength of the adhesive so that theadhesive is cause-d to part around the outlines of the transferredindicia when the carrier sheet is pulled from the receiving surfaceafter the adhesive has been adhered thereto both in the areas of theindicia and in the overlap areas.

5. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia offilm-forming ink printed on a front face of the said carrier sheet andhaving a mechanically breakable bond thereto, and a low-tack pressuresensitive adhesive applied over the said indicia and overlapping ontothe said carrier sheet, the adhesive being a low tack admixture of ahigh-tack adhesive component selected from the class consisting ofacrylic and methacrylic ester land acid polymers and copolymers, vinylether and ester polymers and copolymers, polyisobutylene and polybutene,and a tack reducing low tensile strength deformable component selectedfrom the class consisting of saturated long chain hydrocarbons and acidsand esters and amides thereof and polymer of any of same and long chainalcohols and polyglycols, such that selected individual in- -dicia maybe caused bodily to adhere, by means of said adhesive, to a receivingsurface, on application of indiciatransferring pressure to the rearsurface of the carrier sheet in the region of the selected indicia, thecohesive strength of the adhesive, and its adhesive bond to the carriersheet in the overlap areas, being greater than the adhesive bondestablished between the adhesive and the receiving surface onapplication of said pressure in the areas of the indicia, the saidcohesive strength and adhesive bonds being measured in a directionnormal to the carrier sheet, and the strength of the indicia, and of theadhesion thereof by said adhesive to the receiving surface resultingfrom application of said pressure thereto, being greater than thestrength of the adhesive so that the adhesive is caused to part aroundthe outlines of the transferred indicia when the carrier sheet is pulledfrom the receiving surface after the adhesive has been adhered theretoin both printed and unprinted areas.

6. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia ofprinting ink printed on a front face of the said carrier sheet andhaving a mechanically breakable bond thereto, and a low-tack pressuresensitive adhesive applied over the said indicia and overlapping ontothe said carrier sheet, such that selected individual indicia may becaused bodily to adhere, by means of said adhesive, to a receivingsurface, by indiciatransferring pressure applied to the rear surface ofthe carrier sheet in the region of the selected indicia, the cohesivestrength of the adhesive, and its adhesive bond to the carrier sheet inlche overlap areas, being greater than the adhesive bond establishedbetween the adhesive and the receiving surface on application of saidpressure in the areas of the indicia, the said cohesive strength andadhesive bonds being measured in a direction normal to the carriersheet, the printing ink being formed of a cellulose derivative and aplasticizer therefor and the adhesive being a low-tack admixture of ahigh-tack adhesive component selected from the class consisting ofacrylic and methacrylic ester and acid polymers and copolymers,polyisobutylene and polybutene, and a tackreducing low tensile strengthdeformable component selected from the class consisting of saturatedlong chain hydrocarbons and acids and esters and amides thereof andpolymers of any of same and long chain alcohols and polyglycols, andt-he adhesive having such limited strength in relation to the strengthof the indicia and of the adhesion thereof by the adhesive to thereceiving surface as to part around the outlines of transferred indiciawhen the carrier sheet is pulled from the receiving surface after theadhesive is adhered thereto in both the printed and limprinted areas.

7. As a new article of manufacture, a dry transfer sheet in accordancewith claim 1, wherein said ink is formed of a film-forming polymer and aplasticizer therefor and wherein said adhesive is an admixture of afirst aqueous emulsion formed of two parts of ethylene glycol land afatty acid of l2 to 18 carbon atoms in 12 parts of water and 5 parts ofa second emulsion made up of:

Parts Water 45.27 Non-ionic surface active agent 1.2 vAnionic surfaceactive agent 0.3 Hydroxyethyl cellulose 0.55 Potassium persulphate 0.33Borax 0.35 Copolymer of butyl acrylate (80%) and methyl methacrylate(20%) 52.0

applied as a wet coating of between 1.1 and 2.2 grams per square foot.

8. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia inprinting ink printed on a front face of the said carrier sheet and alow-tack pressure sensitive adhesive applied over the said indicia andoverlapping onto the said carrier sheet, such that selected individualindicia may be caused bodily to adhere, by means of said adhesive, to areceiving surface, by pressure applied to the rear surface of thecarrier sheet in the region of the selected indicia sufficient to breakthe bond between the carrier sheet and the said indicia, the cohesivestrength of the adhesive, and its adhesive bond to the carrier sheet inthe overlap areas, being greater than the adhesive bond establishedbetween the adhesive and the receiving surface on application of thatpressure which is sufficient to establish adhesion of said adhesive tothe receiving surface in the areas of the indicia, the said cohesivestrength and adhesive bonds being measured in a direction normal to thecarrier sheet, and the ad-hesive being so thin and of such limitedstrength as to tear around the outlines of transferred indicia when thecarrier sheet is pulled from the receiving surface after the adhesive inboth the printed and unprinted areas is adhered thereto by pressureapplied as aforesaid.

9. As a new article of manufacture a dry transfer sheet which comprisesa carrier sheet, an image of lmforming printing ink printed on a frontface of the said carrier sheet and having a mechanically breakable bondthereto, and a low-tack pressure sensitive adhesive applied over theimage overlapping onto the said carrier sheet, such that the image maybe caused bodily to adlhere, by means of said adhesive, to a receivingsurface, by pressure applied to the rear surface of the carrier sheet inthe region of the image, the adhesive being an ad-mixture having as afirst component a tacky elastomer and as a second component atack-controlling component shielding the surface of said tackyelastomer, the c0- hesive strength of the adhesive, and its adhesivebond to the carrier sheet in the overlap areas, being greater than theadhesive bond established between the adhesive and the receiving surfaceon application of image-transferring pressure in the area of the image,the said cohesive strength and adhesive bonds being measured in adirection normal to the carrier sheet, the adhesive having such limitedstrength relative to the strength of the image and the adhesion thereofby said adhesive to the receiving surface as to part around the o-utlineof the image when the carrier sheet is pulled from the receiving surfaceafter image-transferring adhesion to the receiving surface is producedby applied pressure both in the area of the image and in the overlapareas.

10. As a new article of manufacture a dry transfer sheet which comprisesa light transmitting carrier sheet, a plurality of separate indicia offilm-forming ink printed on a front face of the said carrier sheet andhaving a mechanically breakable bond thereto, and a low-tack pressuresensitive adhesive applied over the said indicia and overlapping ontothe said carrier sheet, said adhesive having a low tack at pressures ofsubstantially less than about 50 pounds per-square-inch and asubstantial tack at pressures above about 50 pounds per-square-inch,such that selected individual indicia may be caused bodily to adhere bymeans of said adhesive, to a receiving surface, by pressure of at least50 pounds per-square-inch applied to the rear surface of the carriersheet in the region of the selected indicia, the adhesive being anadmixture having as a first component, a tacky elastomer and as a secondcomponent a tack-controlling component shielding the surface of saidtacky elastomer, the cohesive strength of the adhesive, and its adhesivebond to the carrier sheet in the overlap areas, being greater than theadhesive bond established between the adhesive and the receiving surfaceon application of at least 50 pounds per-square-inch in the areas of theindicia, the said cohesive strength and adhesive bonds being measured ina direction normal to the carrier sheet, and the adhesive having suchlimited strength in relation to the strength of the indicia and of theadhesion thereof by the adhesive to the receiving surface as to partaround the outlines of transferred indicia when the carrier sheet ispulled from the receiving surface after the adhesive is adhered thereto-both in the areas of the indicia and in the overlap areas.

References Cited by the Examiner UNITED STATES PATENTS 2/34 Kubin156-230 8/41 Jenkins 106--26 2/51 Carson 26o-28.5

14 A Whittgren 156240 Smith 156-240 McGarry 117-162 Karlan et a1 171-406Shepherd 161-406 MacKenzie 156-230 EARL M. BERGERT, Primary Examiner.

1. AS A NEW ARTICLE OF MANUFACTURE A DRY TRANSFER SHEET WHICH COMPRISESA CARRIER SHEET, AN IMAGE OF FILM-FORMING PRINTING INK PRINTED ON AFRONT FACE OF THE SAID CARRIER SHEET AND HAVING A MECHANICALLY BREAKABLEBOND THERETO, AND A LOW-TACK PRESSURE SENSTIVE ADHESIVE APPLIED OVER THEIMAGE OVERLAPPING ONTO THE SAID CARRIER SHEET, SUCH THAT THE IMAGE MAYBE CAUSED BODILY TO ADHERE, BY MEANS OF SAID ADHESIVE, TO A RECEIVINGSURFACE, BY PRESSURE APPLIED TO THE REAR SURFACE OF THE CARRIER SHEET INTHE REGION OF THE IMAGE, THE COHESIVE STRENGTH OF THE ADHESIVE, AND ITSADHESIVE BOND TO THE CARRIER SHEET IN THE OVERLAP AREAS, BEING GREATERTHAN THE ADHESIVE BOND ESTABLISHED BETWEEN THE ADHESIVE AND THERECEIVING SURFACE ON APPLICATION OF IMAGE-TRANSFERRING PRESSURE IN THEAREA OF THE IMAGE, THE SAID COHESIVE STRENGTH AND ADHESIVE BONDS BEINGMEASURED IN A DIRECTION NORMAL TO THE CARRIER SHEET, THE ADHESIVE HAVINGSUCH LIMITED STRENGTH RELATIVE TO THE STRENGTH OF THE IMAGE AND THEADHESION THEREOF BY SAID ADHESIVE TO THE RECEIVING SURFACE AS TO PARTAROUND THE OUTLINE OF THE IMAGE WHEN THE CARRIER SHEET IS PULLED FROMTHE RECEIVING SURFACE AFTER IMAGE-TRANSFERRING ADHESION TO THE RECEIVINGSURFACE IS PRODUCED BY APPLIED PRESSURE BOTH IN THE AREA OF THE IMAGEAND IN THE OVERLAP AREAS.